- beta-lactam antibiotics. Novel synthetic routes to cephem-ring system from beta-lactam thiazolines via hydrazinothioazetidinones. Franceschi, G., Foglio, M., Masi, P., Suarato, A., Palamidessi, G., Bernardi, L., Arcamone-Cainelli, G. J. Am. Chem. Soc. (1977)